The present invention relates to a piping structure of a working machine. More specifically, the invention relates to a piping structure of a working machine, that can define the bending positions of hoses arranged so as to be flexibly bent on the working machine.
Referring to FIG. 8, a working device 52 equipped with, for example, a quick coupler 51, is swingably attached to an end of an arm 50 of a hydraulic shovel which is a typical working machine, by a shaft member 54. By a swing operation link 53 provided for the arm 50, the working device 52 swings between a lower position represented by a solid line and an upper position represented by a two-dot chain line. The working device 52 is provided with a hydraulic cylinder 51a, to which a hydraulic piping 56 from the arm 50 is coupled. A flexible hydraulic hose 56a is used as the hydraulic piping 56 at an end of the arm 50 so as to be able to follow the swinging working of the working device 52. The hydraulic hose 56a is connected at its one end to a piping 56b secured to the arm 50 and is connected at the other end to the hydraulic cylinder 51a. The hydraulic cylinder 51a is of the double-acting type, and a total of two pipings 56 are provided, one being connected to a head end and the other one being connected to a rod end of the hydraulic cylinder 51a. 
The piping structure of the conventional working machine of above-mentioned construction, however, involves problems as described below.
That is, when the working device 52 swings at an end of the working arm 50, the hose 56a bends between a xe2x80x9cstretched state (indicated by a solid line)xe2x80x9d in which both ends thereof are separated away from each other and a xe2x80x9cslackened state (indicated by a two-dot chain line)xe2x80x9d in which both ends thereof are brought close to each other due to the swinging motion, and is liable to come to contact with the working arm 50 or the working device 52. In the xe2x80x9cslackened statexe2x80x9d, in particular, the hose 56a hangs down between the working arm 50 and the working device 52 or extends over a lateral side of the working arm 50, often being caught between the working arm 50 and the working device 52 or coming in contact with the surrounding obstacles during the work. Consequently, the life of the hose is shortened or the hose is damaged.
The present invention has been accomplished in view of the above-mentioned fact, and its technical assignment is to provide a piping structure of a working machine which makes it possible to prevent the hoses that are so arranged as can be flexibly bent on the working machine, from being damaged.
In the present invention, as a piping structure of a working machine to solve the above-mentioned technical assignment, there is provided a piping structure of a working machine, comprising a guide cylinder in which is slidably inserted an intermediate portion of a hose that is so arranged as can be flexibly bent on the working machine, to define the bending position of the hose.
In the piping structure according to the present invention, the xe2x80x9cslackingxe2x80x9d of the hose is located at a position where the hose is hardly damaged by using the guide cylinder in which the intermediate portion of the hose is inserted.
In a preferred embodiment, the guide cylinder has, at the end on one side or at the ends on both sides thereof, a bending portion for defining the direction of the hose that moves in or out.
The direction of the hose is determined by the bending portion.
According to another embodiment, a guide member is provided near the open end of the guide cylinder to define the direction of the hose that moves in or out.
The direction of the hose is determined by the guide member.
In a preferred embodiment, provision is made of an urging means for urging the hose toward either a direction to move in to the guide cylinder or a direction to move out from the guide cylinder. The urging means is provided with a tension spring coupled to the hose. According to another embodiment, the urging means is provided with a coil spring in which the hose is inserted. Further, the guide cylinder is formed of a steel pipe.
The urging means urges the hose to move in into, or move out from, the guide cylinder, so that the hose smoothly moves in into, or moves out from, the guide cylinder. Further, the guide cylinder is formed of a steel pipe to protect the hose from damage caused by the interference with foreign matters.
In a preferred embodiment, the working machine includes an arm and a working device swingably coupled to an end of the arm, the guide cylinders are provided on the arm, and hoses are passed into the guide cylinders to connect the arm with the working device.
This prevents the hoses arranged between the arm and the working device of the working machine from being damaged.